Sour Cream

Sour cream is a dairy product made by fermenting regular cream with lactic acid bacteria, which thicken the cream and produce the lactic acid that gives it its characteristic tart taste and name; traditionally it developed naturally when cream skimmed from milk was left to ferment at moderate temperature, which both preserved it and gave it its tang. In the United States, FDA regulations require commercial sour cream to contain at least 18 percent milk fat before other ingredients are added and 14.4 percent afterward, with a minimum total acidity of 0.5 percent, and it may include approved stabilizers and thickeners; it must be refrigerated, and an opened container typically lasts 7 to 10 days. It is used as a condiment, an ingredient in sauces, soups and baked goods, and a topping for dishes such as tacos, nachos and burritos, and features prominently in Eastern European, Ashkenazi Jewish and Tex-Mex cooking.